This invention relates to manually operated fluid valves for controlling the operation of other fluid valves and, more particularly, to a manually operated fluid valve which is designed to require two-hand operation to prevent accidental actuation.
Manually operated fluid valves for controlling the operation of other fluid valves are well known. Such valves have been used with pilot valves providing a manual substitution for the operation thereof in order to control a main fluid valve during set up, testing, or other operations of the main valve. However, I have discovered that such prior known override valves could be accidentally actuated making their use in certain applications less desirable.
First, prior known manual override valves for pilot valves have been operable using only one hand. Modern safety considerations dictate against such singlehanded operation in order to prevent inadvertent operation of the main fluid valve. Similarly, the prior known valves could be inadvertently struck or bumped initiating operation of the main fluid valve and hence some piece of machinery controlled by that fluid valve at undesired times thereby creating a safety hazard.
It has also been discovered that it is advantageous in certain applications to provide means for locking an override valve in one position and to provide for simple removal of such locking apparatus. Although certain of the prior known valves could be locked in one position to continuously "override" a pilot valve, conversion of such prior valves to remove the locking apparatus was often extremely difficult and impractical.
Further, it has been found advantageous to determine the position of the manual override valve from a large distance away from the pilot and/or main valve. The actual valve position of the prior known override valves is extremely difficult to determine from any more than a short distance away.
Thus, I have determined the need for a valve which is capable of being converted from locking to nonlocking modes, which is compatible with safety requirements to prevent inadvertent operation thereof by bumping or with one hand, and which provides for accurate determination of its position from large distances away from the valve.